Generally speaking, any electronic device (including electronic equipment) must be powered by an external power source except for employing the electronic cells. Thus, how to convert the voltages offered by the different external power sources (AC or DC) into the certain form and within the proper range so as to be properly employed by the electronic device (including electronic equipment) is an important issue.
The power converter is just such a device for the above-mentioned requirements. Usually, the power converters can be further divided into the AC-DC converters, the DC-DC converters, etc. according to the voltage converting types of the converters. The users can make the proper choices of different converters to cope with the different output voltage requirements.
In general, one of the purposes of the power converter is to convert the given voltage, which does not meet the input voltage requirements of the electronic device (including electronic equipment), into the proper form and value of the desired input voltage such that the output voltage of the power converter could be employed by the electronic device (including electronic equipment) properly. Base on the considerations of saving the space and lowering the costs, there are power converters suitable for applying to various electronic devices (including electronic equipments) having different input voltage requirements proposed in the prior art. For example, there are power converters for providing different output voltage values through employing the switching device, in which the different output voltage values are offered through changing the position of the switching devices. Please refer to FIG. 1, it shows the schematic diagram of the power converter employing a switching device to change the output voltages in the prior art. In which, the power converter 10 includes a main body component 11, a switching device 111 on the main body component 11, and a power cord 12 having an input power cord 121 and having an output power cord 122. Basically, such a design would resolve the drawbacks of the prior art that a plurality of power converters are required for applying to the various electronic devices (including electronic equipments) having different input voltage requirements. But, when the above-mentioned switching device is employed, it is quite possible that the electronic device (including electronic equipment), which uses the output voltage generated by the power converter through changing the position of the switching device, is damaged due to that the user chooses an incorrect output voltage by mistake especially when the incorrect output voltage is higher than the voltage required by the electronic device (including electronic equipment).
To improve the aforementioned drawbacks, a power converter is proposed in P. Jakubowski (U.S. Pat. No. 5,347,211), which includes a plurality of keys each having an electronic element inside for inserting into the keyway of the proposed power converter to be electrically connected to the power converter such that the output voltage value is decided by the specific value of the electronic element (which is one of a resistor, a capacitor, and an inductor). When the various keys each having a different electronic elements are selectively inserted, a set of the different output voltage values are generated accordingly.
But the aforementioned power converter as proposed in the '211 Patent still has the following drawbacks:
1. As for the key having an electronic element inside, the heat-dissipating space inside the key is more limited than that of the power converter. While the key is employed for a relatively longer time period, either the key is damaged or the life-span of the key is shortened due to that the heat is generated inside the key by the electronic element and the heat-dissipating condition inside the key is relatively poor. When the key is broken (short-circuited or open-circuited), the output voltage value of the power converter is abnormal, and the electronic device (including electronic equipment), which employs the output voltage of the power converter, would be damaged.
2. To each required output voltage, the corresponding key must have a different electronic element. If N different output voltages are required, N extra electronic elements are needed such that the design complexity of the electronic circuit and the number of electronic elements employed are increased, and which should be further simplified.
3. In the prior art, no over-current and over-voltage protections are offered simultaneously to the output voltage. When the output voltage value is abnormal, the electronic device (including electronic equipment), which employs the output voltage, would be damaged. If an over-current protection and an over-voltage protection are offered at the same time, the electronic device (including electronic equipment), which employs the output voltage, would be provided with an over-current protection and an over-voltage protection simultaneously for avoiding the damage when the power converter is damaged and the output current and output voltage of which are abnormal.
Keeping the drawbacks of the prior arts in mind, and employing experiments and research full-heartily and persistently, the applicant finally conceived the power converter system having a plurality of adaptor units for generating multiple output voltage values.